AIDS researchers edge toward 'cure' Combination of drugs can reduce virus below detectable level

July 05, 1996|By LOS ANGELES TIMES

For the first time since the AIDS epidemic began sweeping across America and the world, physicians think they may have the weapons to place them on an equal footing with the deadly virus.

While cautious about using the word "cure," researchers gathering Sunday in Vancouver, British Columbia, for the 11th International Conference on AIDS are optimistic that they can begin to bring the epidemic under control.

In new studies that will receive their first formal presentations at the conference, researchers have found that potent combinations of new and old drugs can reduce HIV concentrations in AIDS victims to levels below detectability. This allows patients' immune systems to rebound to health -- an unprecedented accomplishment.

To their astonishment, scientists are for the first time even talking guardedly about the prospect of eradicating the virus from victims' bodies completely: a "cure" that once seemed hopelessly beyond reach.

"If you had asked me in January, 'Can you eradicate HIV infection?' I would have laughed in your face," said Dr. Julio Montaner of the University of British Columbia. "But now we've been able to demonstrate that we can effectively suppress viral production. That is leading to a dramatic change in how we think about the disease."

"We are at a crossroads in the history of the epidemic," added Dr. Martin Shechter, co-chairman of the conference. "At past conferences, there was a lot of gloom and doom and bitter disappointment. The tenor of this conference should be one of cautious optimism. People haven't been this excited for a long, long time."

The new treatments are so promising, in fact, that some experts now argue that everyone should have a yearly AIDS test to detect an infection as early as possible. When an infection is detected, said Dr. Douglas Richman of the University of California, San Diego, physicians should attack it "early and hard."

AIDS activists, however, argue that the new combination treatments, for all their promise, have a dark side as well. They have several powerful side effects, and their cost puts them out of reach of many Americans, much less AIDS victims in developing countries.

The basic numbers behind the epidemic also have only gotten bleaker in the two years since the last international conference. In the United States, an estimated 650,000 to 900,000 people are infected with the virus -- one in every 300 people over the age of 13, according to epidemiologist John M. Karon of the Centers for Disease Control and Prevention.

An estimated 55,000 Americans died of AIDS-related infections in 1994, the most recent year for which data is available, bringing the total to more than 325,000, Karon said.

But the U.S. numbers are dwarfed by those elsewhere in the world. According to the United Nations, more than 90 percent of all HIV-positive adults live in developing nations. An estimated 21 million people worldwide have contracted the virus that causes AIDS. About 4.5 million people have full-blown AIDS, and more than 4 million people have died from it.

In the past, physicians could do little for AIDS patients other than ameliorate symptoms. The drug AZT could knock down viral concentrations in victims for a time, perhaps a year or more, but xTC the shifty virus was generally able to mutate its way out of control.

Now, however, nine different AIDS drugs are being sold in the United States, five of them approved in the last six months. Six of the drugs, including AZT, are "reverse transcriptase" inhibitors. These prevent the virus from copying its genetic material, the first step in making more viruses.

These drugs have provided short-term control of the virus, but HIV has always eventually found a way to develop resistance to them. But three other new drugs called protease inhibitors have dramatically changed the balance of power.

The protease inhibitors attack another enzyme that also is crucial to HIV's reproduction. When the machinery of an infected cell manufactures the 17 proteins that make up the body of HIV, those proteins are all joined together in one long strand. They cannot form new viruses until they are snipped apart by a scissors-like enzyme called HIV protease.

The newly developed protease inhibitors jam the scissors portion of the enzyme, thereby blocking viral replication.

Alone, these new drugs are not much better than the reverse transcriptase inhibitors. But when combined with two reverse transcriptase inhibitors in a three-drug combination, they produced an unexpected wallop.

Still, many researchers caution that the AIDS community has been optimistic in the past, only to have their hopes shot down when the virus came up with new tricks. Some are particularly nervous when researchers talk about the prospects for a cure.

"I refuse to say that word at this point," said Dr. Richard D'Aquila of Massachusetts General Hospital in Boston. Perhaps it is more appropriate, added Dr. Roy Gullick of the New York University Medical School, to talk about "turning AIDS into a long-term manageable and treatable disease, much like hypertension and diabetes."

Pub Date: 7/05/96

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